An LED light strip refers to the assembly of LED lights on a strip-shaped FPC (flexible printed circuit) or PCB hard board, and is named strip as resembling a tape in shape. LED light strip has gradually emerged in various decoration industries as being credited for its long service life (a normal life of 80,000 to 100,000 hours), energy-efficiency and environmentally friendliness.
LED light strips mainly include high-voltage light strips and low-voltage light strips. The high-voltage light strip is directly connected to 220V mains power, and suffers severe light attenuation and instability due to instability of the mains power. The low-voltage lamp is generally 12V or 24V with unstable voltage drop, wherein a considerable head-tail voltage difference exists when under single-ended power supply; a significant difference in head and tail brightness and extremely poor uniformity in light emission also exist when under service voltage, thereby causing a continuous decrease in brightness as the length of the light strip increases. As a result, the usability of existing commercial low-voltage light strips are heavily affected by limitation of length, which in this case limits a connection length (<5 meters) and a length of head-tail power supply (<10 meters), thereby failing to meet the demands of users.
On the other hand, existing LED chips are made of gallium nitride with a refractive index of 2.2 or higher, while the refractive index of the encapsulants used for packaging is usually 1.4-1.5. Encapsulants with high refractive index are commonly used for packaging in order to reduce light loss, a problem yet to be solved as the difference between the refractive indexes of the encapsulant and LED chip still remains large. Further light loss also occurs when light is refracted from the encapsulanet into the air as the difference in refractive index also exists for the two. As a result, light-emitting efficiency of LED light strip is considerably impaired.
Therefore, the development of an ultra-long, low-voltage light strip with high light-emitting efficiency and uniform illumination has become an urgent need in the LED field.